A Russian hacker is claiming he broke into LinkedIn’s network and stole nearly 4.5 million password hashes from user accounts. LinkedIn is investigating the claims, but some LinkedIn users claim they have found their hashes in a file the hacker posted online. The file did not contain usernames of account holders. LinkedIn uses an encryption algorithm that converts a password into a long string of letters and numbers. These strings are what the hacker took. By knowing which algorithm LinkedIn uses, and users’ propensity to use easy-to-guess passwords, such as common words found in the dictionary, it can be a simple matter of cracking the hash.